Debarking machine of the hollow rotor type

ABSTRACT

The invention relates to a debarking machine comprising a hollow rotor carrying debarking tools pivotable to and from the axis of the rotor. The machine is of the type in which hydraulic power transmitting means are adapted to act upon the tools to move them onto the axis of the rotor, while pressure accumulator means are mounted on the rotor to supply pressurized liquid to said power transmitting means.

United States Patent Inventor Nils OlofJohansson Vallingby, Sweden Appl. No. 808,065 Filed Mar. 18, 1969 Patented Jan. 5, 1971 Assignee Brundell Och Jonsson AB,

Gavle, Sweden, I a corporation of Sweden Priority Mar. 25, 1968 Sweden No. 3940/1968 DEBARKING MACHINE OF THE HOLLOW ROTOR TYPE 2 Claims, 4 Drawing Figs.

US. Cl 144/208 Int. Cl B271 1/00 Field of Search .l 144/2085,

[56] References Cited UNlTED STATES PATENTS 3,196,912 7/1965 Brundell et alt 144/208 3,333,615 8/1967 Robbins 144/208 3,361.168 H1968 Brown 144/208 Primary Examiner-Donald E. Schran Attorney-Bauer and Goodman ABSTRACT: The invention relates to a debarking machine comprising a hollow rotor carrying debarking tools pivotable to and from the axis of the rotor. The machine is of the type in which hydraulic power transmitting means are adapted to act upon the tools to move them onto the axis of the rotor, while pressure accumulator means are mounted on the rotor to supply pressurized liquid to said power transmitting means.

'PATENTEU JAN 5x971 SHEET 2 OF 2 The Swedish Pat. specification 179,777 describes such a debarking machine in which hydraulic cylinders are provided to cause the tools to resiliently engage the surface of a log passing through the rotor, and said cylindcrs'arethen connected to a hydraulic-pneumatic pressure accumulator in which gas and liquid are separated'by a diaphragm.

Further, the U.S. Pat. No. 3,333,615 describes a similar de-- barking machine in which the tool force maybe changed by increasing or reducing the amount of liquid in a hydraulicpneumatic pressure accumulator by means ofa pump and a valve both operated electrically. Thus, the force of the tools 7 may be changed continuously until the desireddebarking effect is obtained. Howevenan inconvenience of this device is that the readjustment needs a rather long "time so that the required tool force is often not obtained until a whole log has been incorrectly debarked in passing through the rotor.

The object of the invention is toprovide a'device bymeans of which the force actingon the tools can be changedstepwise and practically instantaneously. For that purpose, at least two pressure accumulators having different pressure levels are provided to be optionally connected to'the hydraulic power transmitting means by. setting valves, whereby a stepwise change of the hydraulic force acting upon the tools is made possible.

The invention will be further described. with reference to theaccompanying drawings, in which: p

HO. 1 shows diagrammatically how'a debarking tool may' be operated by means of one of two pressure. accumulators;

FIG. 2 shows a similar view of an embodiment with three pressure accumulators;

FIG. 3 showsan axial section through a portion of thecylimdrical rotor wall and adjacent portion of a stator; and

FIG. 4 shows diagrammatically a radial section through a debarking rotor, in which the device shown in H6. 2" is mounted.

In FIG. 1, 5 designates a debarking tool secured to a rotatable shaft pivot 6. The tool is show'n'in its initial position before the end surface of a log 7 adapted to be fed intofthe rotor not shown. An arm 8 secured to the shaft pivot 6 'a'nd projecting radially therefrom has its outer end linked-to'a; piston 9 which is movable'in a hydraulic cylinder 10. The inward 'mo vement of the tool 5 into the initial position shown is limited in that the arm 8 hits a rubber-coated stop'm ember 11 secured to the rotor.

A conduit 12 connects the rear end of-the cylinder to one end of a cylinder l3which'contains a movable piston 14, and another conduit extends from the conduit 12 m another cylinder l6'likewise containing a movable 'pistoh' l7.'A- normally open valve. l8 disposed in the conduit 15 is closed on supply of current to a solenoid 19, but the V3IVQ18'lS bypassed by a branch conduit'1which contains a nonreturn valve 21 opening in the direction away from the cylinder. 16. The two cylinders 13 and 16 are ada'ptedto functionjas'pressure accumulators. and for this purpose their rear endsare provided with nipples for supply of pressurized gas'up Ito'the' desired pressures. Thus. the space 23 behind the piston is filled with gas of high pressure so that'in the initial position shown thelpiston 14 has been moved into contact with-the fo're end wall of the cylinde'r 13. The space 24' behind the-piston 17' in the-cylinder 16' is filled'with gas of lower pressure, but the piston 17 isin tin-intermediatepositionwbecause-thefore" cylinder spacel 25, the system of conduits l2, 15;20 and the cylinder space inside of the piston 9 are filled with an amount of liquid measured correspondingly.

The debarking tool 5 .is preferably ofth e'iso-called self-'- opening type. ie, it has an edge directed'to'theend surface of the advanced log, and because of its engagement'this edge causes the tool to climb onto th'e'cylindrical surfaceofthe log; Thus, when the rotor is rotated'clockwise'in-FlG. l, the tool is action of the gas pressure prevailing in thelow pressure accuits initial position in FIG. 1, the movemeht of the piston 9' causes the piston 14 of the high-pressureaccumulator 13 to be forced back, as the flow of liquid to the low-pressure accumulator 16 is now blocked, and'the tool'is then actuated by the high pressure in the pressure gas'chainber 23. However, a special case occurs, if the solenoid valve 18 is closed during the debafking of a log, the diameter of which decreases progressively. As the piston 14' of the high-pressure accumulator I} initially is in its inoperative position, it'cannot force any liquid into'the cylinder 10; a'rid thusthe'cylinder l0 is'still influenced by the low pressure only; When the tool is rotated anticlockwise because of the decreasing diameter of the log, the required amountof liquid is suppliedfrorrt the space 25 of the low-pressure cylinder 16 through the nonre'turn valve 21f,

which opens in this direction, as mentioned above. When the log has passed through the rotot and the tool 5 moves back to its initial position (FIG. 1), liquid is" still supplied to the cylinder 10 from the low-pressure accumulator 1'6, and'not until the tool is lifted bythe next log does the communication with the low-pressure accumulatorl6 becomeblocked, so that the piston 14 of the'high-pressdre accumulator 13 is pressed backwards agaiflstthe action of the high pressure in the space 23.

increase the forceimrn'ediately but; on the otherfhandlsaid force mayalways be reduced'imrhediatelyby openirig thes e noid valve 18. Because of thegas pressure in the'space23the" :piston l4'is' then immediately 'movedintoits.iriopei-ativeend .in any situation. lfa-higH-pr'essure' set'istoo greatiacons'idera' other hand; it might not be possible'to carry out-a required in.-

time.

The embodiment shown in FIG. 2 fdiffers fror nfthe bn'in FIG.- -l only in th'at'a furtherpressureiaccumulator has'ibeen space-23 of which is filled with gasupitoa prcssure betlwee'n ls inserted in the'conduit' 261s controlledby a solenoid and in'the same wayas in H0; I'thevaIVe 18' is bypassed by a branch conduit20'-containihg a nomium; valve2l" which ln theinitialpositioii shown, the piston 14"of the'medium pressure'accumiilator "13' is held in inoperative end posi tion inthe'sarrieway as't'he pis'itori 14 of the high pressure accumulator 13; but also inthiscase'the piston i Tof thelo pressure accumulator l66ccu'pies an intermediate position. If

On the other hand, if the solenoid valve'l 8 is closed during Consequently; in'certain ci'rcums'fances it is not possible to" positionwhile transferring a corresponding 'amount'of 'liquid to the low-pressure accumulator "16. In fact; the possibility of quickly reducing the force acting onthe tools is in'ore'impbr tantthan-a possibility of increasing the pressli're immediately :added; so that-it becomes-possible to choose between three differentFIeveIs of pressure'l 'Where-convefnient?the reference numeials have been-used.- In FIG! 2,}fa cgihdtii't 26'- 3 eXte'nds-fromthe conduit 15w an accumulator 13", the gas permits a flowin the directionaway from the accuniiilator 13.

the tool 5 is to be brought into engagement by means of the accumulator 13, the solenoid valve 18 of the low-pressure accumulator 13 is to be used, both solenoid valves 18, 18 are closed. Of course, still more accumulators may be mounted in the same way, in that the general rule is to close the solenoid valves of all accumulators having a lower pressure than the one desired. For the rest, the function is in principle the same as that of the embodiment described in connection with HO. 1.

In the described devices for stepwise change of the operating forces of the tools, there is no equalization of pressure between the various accumulators because of leakage or redistribution of liquid at the resetting of valves, while a log is present in the rotor. In such cases, where a determined amount of liquid is forced into an accumulator having a lower pressure, the initial state is reestablished, as soon as the tool has assumed its initial position. Further, the device described has the advantage that any volume changes in the hydraulic system because of leakage to the surroundings, variations of temperature or an adjustment of the stop member 11 are automatically compensated for by the quantity of liquid in the foremost space 25 of the low-pressure accumulator 16. The maximum pressure in the system is influenced only by a possible leakage of gas from the high-pressure accumulator space 23.

FIG. 3 is intended to illustrate how in the known way the electric current may be transmitted to the solenoids mounted in the rotor. 27 designates the cylindrical wall of the rotor,

which is externally provided with peripheral grooves to receive driving belts 28. Beside these belts, the rotor carries three slip rings 29, 30, 31 spaced axially and cooperating with resilient brushes 32 mounted on the inside of the surrounding stator 33. Two of the slip rings, 29 and 30, are insulated and each of them is connected to one phase of a source of alternating current, while the third slip ring 31, which need not be insulated, may be connected to earth. Often the third slip ring 31 may be entirely dispensed with in that the rotor may serve as earth.

FIG. 4 shows a radial section through a rotor provided with three debarking tools 5 as well as the device shown in FIG. 2. Here, the tools are shown lifted on to the surface of a log 35 introduced into the rotor 34. The cylinders of the pistons 9 linked to the tool arms 8 are by means of conduits 36 permanently in communication with a liquid distribution duct 37 extending in a circle around the inner periphery of the rotor. The three accumulators 13, 13' and 16 are connected to said distribution duct 37 by means of the conduits 12. 26 and 15, respectively. By way of the slip rings 29-31 each of the two solenoids l9 and 19' is connected between earth and one of the phases of the alternating current. In FIG. 4, the switches 38, 39 are open, and thus the solenoid valves 18, 18' are also open, so that the tools 5 are influenced by the low-pressure accumulator 16, the piston 17 of which, in the position of the tools shown, has been moved backwards in relation to the initial position shown in FIG. 2. Owing to the distribution duct 37 all the tools are actuated simultaneously by the adjusted pressure. The slip rings 29-31 mounted around the rotor are here shown in a diagrammatic perspective view.

The device described may be modified in several respects within the scope of the invention. For instance, the gas pressures in the accumulators may be replaced by springs inserted to act upon the movable pistons.

lclaim:

1. A debarking machine comprising a hollow rotor carrying debarking tools pivotable to and from the axis of the rotor. hydraulic power transmitting means adapted to act upon the tools to move them onto the axis of the rotor, and pressure accumulator means mounted on the rotorto supply pressurized liquid to said power transmitting means, characterized in that at least two pressure accumulators having different pressure levels are provided to be optionally connected to the power transmitting means by setting valves, whereby a stepwise change of the hydraulic force acting upon the tools is made possible. I

2. A debarking machme as claimed m claim 1, characterized in that the accumulator having the highest pressure level is connected to the power transmitting means through a permanently open conduit, in that each accumulator having a lower pressure level communicates with with said power transmitting means through a conduit containing a solenoidoperated shutoff valve, in that a branch conduit bypassing the shutoff valve contains a check valve opening in the direction from its accumulator, and in that the amount of liquid in the whole hydraulic system is measured such that only the lowest pressure accumulator contains a small amount of liquid, even when the tools are in an inoperative position with their edges close to the axis of the rotor. 

1. A debarking machine comprising a hollow rotor carrying debarking tools pivotable to and from the axis of the rotor, hydraulic power transmitting means adapted to act upon the tools to move them onto the axis of the rotor, and pressure accumulator means mounted on the rotor to supply pressurized liquid to said power transmitting means, characterized in that at least two pressure accumulators having different pressure levels are provided to be optionally connected to the power transmitting means by setting valves, whereby a stepwise change of the hydraulic force acting upon the tools is made possible.
 2. A debarking machine as claimed in claim 1, characterized in that the accumulator having the highest pressure level is connected to the power transmitting means through a permanently open conduit, in that each accumulator having a lower pressure level communicates with with said power transmitting means through a conduit containing a solenoid-operated shutoff valve, in that a branch conduit bypassing the shutoff valve contains a check valve opening in the direction from its accumulator, and in that the amount of liquid in the whole hydraulic system is measured such that only the lowest pressure accumulator contains a small amount of liquid, even when the tools are in an inoperative position with their edges close to the axis of the rotor. 